On the multiple-access capability of a shared Rayleigh wireless channel with binary feedback

In this paper we consider the capacity of a Rayliegh faded wireless channel that is shared by K independent transmitter-receiver pairs. No cooperation is assumed between the different pairs. We examine the possible gain in the sum rate capacity when a binary side information is passed by each receiver to its corresponding transmitter on whether the instantaneous local signal-to-interference-plus-noise-ratio (SINR) is greater or less than a given threshold, and transmitters adapt their transmission power accordingly. It is shown that a substantial improvement in the channel capacity can be achieved by using this "opportunistic" transmission strategy. Our numerical results reveal that the total sum capacity increases linearly with the logarithm of the number of users sharing the channels.